Cyclic neutropenia is a rare blood disorder characterized by recurrent episodes of abnormally low levels of neutrophils (a type of white blood cell) in the body. Neutrophils are instrumental in fighting off infection by surrounding and destroying bacteria that enter the body. Symptoms of cyclic neutropenia may include fever, a general feeling of ill health, and/or sores (ulcers) of the mucous membranes of the mouth. Individuals with low levels of neutrophils (neutropenia) are highly susceptible to recurrent infections. Cyclic neutropenia may be inherited or acquired. Some cases are present at birth and appear to occur randomly for no apparent reason (sporadic). Inherited cases appear to be transmitted in an autosomal dominant fashion and are caused by mutations in the ELANE gene.